I've used them before but they were fine-mesh. Always floating... I tried weighing them down but still they floated. Wondered if there was any sort of decent extraction? The brew didn't seem very hoppy to me.

Considering coarse mesh or might even make some out of surgical sponges. Also have some "Leggs" knee-high stockings but they float too.

Is there a method and approach that is more successful that others?

How much weight are you putting in the bag? I've used some 316 SS ingots from my pyro chemical ball mill to weigh down the cheap knee-hi hose bags I sometimes use. Obviously, it depends on how many ounces of hops are in the bag as to how much weight you need. Part of the problem from my unscientific observation is that bubbles get trapped inside the bags during the boil, especially when it's fine mesh, and that exacerbates the buoyancy issue. Keep adding weight and you'll get 'er to sink!